Method and equipment for the pyrolysis and synthesis of hydrocarbons and other gasesand arc heater apparatus for use therein



June 8, 1968 CHIKARA HIRAYAMA ETAL 3,

METHOD AND EQUIPMENT FOR THE PYROLYSIS AND SYNTHESIS OF HYDROCARBONS AND OTHER GASES AND ARC HEATER APPARATUS FOR USE THEREIN Filed April 6, 1965 4 Sheets-Sheet 1 H62. 5 FIG-IA. C 2H 0. h

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6A 6B 6C 226 FlG-IB INVENTORS r234 Chikcru Hiruyomo a George A. Kemeny as HR 9Y Z2 GENERATOR 7 GENERATOR ATT NEY June 8, 1968 CHIKARA HIRAYAMA ETAL. 3,339,139

METHOD AND EQUIPMENT FOR THE PYROLYSIS AND SYNTHESIS OF HYDROCARBONS AND OTHER GASES AND ARC HEATER APPARATUS FOR USE THEREIN Filed April 6, 1965 4 Sheets-Sheet 2 June 1968 CHIKARA HIRAYAMA ETAL 3,339,189

METHOD AND EQUIPMENT FOR THE PYROLYSIS AND SYNTHESIS OF HYDROCARBONS AND OTHER GASES AND ARC HEATER APPARATUS FOR USE THEREIN Filed April 6, 1965 4 Sheets-Sheet :5

BIASED RECTIFIER HEATER June 1968 CHIKARA HIRAYAMA ETAL 3,339,189

METHOD AND EQUIPMENT FOR THE PYROLYSIS AND SYNTHESIS OF HYDROCARBON S AND OTHER GASES AND ARC HEATER APPARATUS FOR USE THEREIN Filed April 6, 1965 4 Sheets-Sheet 4.

HEATER ARC HEATER TURBULENT MIXING CHAMBER HEATER FIGQB .3292. QQQ 348 \AJk/Jlk/ United States Patent METHOD AND EQUIPMENT FOR THE PYROLYSIS AND SYNTHESIE 0F HYDROCARBONS AND OTHER GASES AND ARC HEATER APPARATUS FOR USE THEREIN Chikara Hirayama, Franklin Township, Murrysville, and George A. Kerneny, Franklin Township, Export, Pa., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Apr. 6, 1965, Ser. No. 446,012 22 Claims. (Cl. 260679) ABSTRACT OF THE DISCLOSURE An arc heater or are heaters are used to pyrolize a process gas, and means is provided to thereafter quench the gas to a temperature at which a desired recombination product is present in substantial proportion. Additional means may be used to further quench the gas to prevent further undesired chemical reactions. In one embodiment, arc heater apparatus is arranged to supply an output of alternate relatively hot pyrolized masses of gas and relatively cold masses of gas, and the relatively cold masses of gas are used to quench the relatively hot masses. In another embodiment, two are heaters are energized from one alternating current source; each arc heater has rectifier means in series therewith, the rectifier means being oppositely poled with the respect to each other, so that both are heaters supply outputs of alternate relatively hot and relatively cold masses of gas, the relatively cold mass of one are heater occurring simultaneously with the relatively hot mass of the other are heater and being used to quench the relatively hot mass. In a further embodiment six are heaters are employed, connected in pairs by oppositely poled rectifiers to the three phases of a three phase alternating current source and all delivering their outputs to a common mixing chamber.

This invention relates to a method and apparatus for the pyrolysis and synthesis of hydrocarbons and other gases and, more particularly, to an improved method and apparatus utilizing arc heater equipment for the pyrolysis of a gas to be decomposed, the same are heater equipment being used for the initial cooling of the dissociated hydrocarbons to cause the atoms to recombine to form a desired gas which is thermodynamically stable at the cooling temperature.

In particular, the method and apparatus are suitable for the conversion of methane and other hydrocarbons to acetylene and other gases.

In recent yea-rs a relatively efiioient process for obtaining acetylene from a readily obtained gas, for example, methane, has included a first step to pyrolize the methane, to thereafter inject a cool gas into the dissociated gas to cool the mixture to a predetermined temperature corresponding approximately to equilibrium at maximum acetylene concentration, or to a temperature within the stable recombination temperature range of the desired product, and thereafter rapidly further quenching the gas mixture containing the desired product in order to freeze out or obtain the desired gas.

One of the useful applications of a plasma heater, such as a plasma gun or a rotating arc heater, is in such a conversion of a hydrocarbon, for example, methane to acetylene. When the gas to be processed passes through the heater, the gas is heated to a temperature above 3500 K. and is dissociated to the gaseous elements. For example, the hydrocarbons dissociate primarily to carbon and hydrogen atoms. As the gas discharges from the heater, it is cooled rapidly and the atoms recombine to "ice form the species which are thermodynamically stable :at the exit gas temperature.

Equilibrium calculations for a system containing hydrogen and carbon at a total pressure of one atmosphere show that acetylene, C H is a stable recombination species between 2500 K. and 4200 K., and that its maximum concentration in this mixture is found at temperatures in the neighborhood of 3600 K. At a total pressure of 10 atmospheres the maximum concentration of 0 H; will be at around 3800 K., and at atmospheres it will be at around 4000 K. The maximum concentration of acetylene in this temperature region, depending on the C:H ratio and on the pressure of the system, varies from slightly less than ten to approximately fifteen volume percent, with the other components being mainly H and. H Upon cooling, the H atoms recombine to form H so that the C H concentration, should this species be cooled without change, will increase. When methane, CH is the hydrocarbon gas, the theoretical C H concentration in the cooled product is 25 volume percent. However, acetylene is thermodynamically unstable at temperatures below about 2500 K., so that as it cools this gas tends to undergo rapid chemical reactions to form carbon and hydrogen, or to form polymeric materials, thus lowering the yield of acetylene. Therefore, it is highly essential to rapidly quench the gas from about 3600 K. to below 1000 K. in about 1 milliseconds, and subsequently to below 500 K. in less than 1 second in order to freeze the C H An effective prior art method which is used to quench the gas is one in which a cool, higher molecular weight hydrocarbon is injected into the hot gas stream at the nozzle of an arc heater to cool the gas to about 2000" K., followed by a sprayed-water quench to rapidly cool to about 500 K. The acetylene is still in a gaseous state at this temperature, and is readily separable from the Water.

Apparatus for obtaining acetylene from methane according to this prior art method and employing an electric arc to effect pyrolysis is shown and described in Belgian Patent No. 604,989, issued to the Du Pont Chemical Co., June, 1961. A similar process is disclosed in United States Reissue Patent Re. 25,218 dated Aug. 7, 1962 issued to E. Schallus et al. for Process for Carrying Out Endothermic Reactions at High Temperatures. Reference may also be had to United States Patent No. 2,790,838 issued to R. Z. Schrader for Process for Pyrolysis of Hydrocarbons. In the Belgian patent, there is described apparatus which includes an arc chamber in which a rod electrode is coaxially disposed within a cylindrical electrode, the are taking place within the cylin drical electrode. A coil disposed adjacent the cylindrical electrode in the region of the arc causes the arc to rotate substantially continuously in a substantially annular path. The process hydrocarbon is injected into the cylindrical electrode at one end thereof and flows past the are Where it is heated to a certain temperature. A. cooling hydrocarbon, for example, propane, is injected into the heated methane at a point closely adjacent the are by inlets to the cylindrical electrode. From this area of the cylindrical electrode, the mixture of disassociated methane and propane passes rapidly down the electrode to an area where a water jet quickly further cools the gases to, for example, 300 C., and as rapidly as possible thereafter, the gases are conducted from the electrode chamber at nonreaction temperatures. It appears from a study of Belgian Patent 604,989 that uniform heat is obtained from the rotating electric arc. In connection with steps in the process, US. Patent Re. 25,218 discloses electric arc apparatus for heating a gas such as hydrogen. Whatever the process of heating, however, the reaction zone contains nonessential gases, and the optimum proportion of the desired product can only be obtained by efiicient and rapid cooling of the gases to a temperature where the desired product is substantially in equilibrium, or is a stable recombination product, and thereafter further cooling to obtain the separation of the desired product from the mixture.

Our invention represents an improvement over the abovedescribed prior art method and apparatus and constitutes an advance in the art.

The heart of our invention is that we obtain increased efficiency by eliminating nonessential gases from the reaction zone where synthesis occurs.

To heat and pyrolize the hydrocarbon we utilize an arc heater in which the arc is produced by an alternating current, and the instantaneous temperature to which gas is heated inside the arc chamber automatically follows the power curve of the are, which power curve goes to zero at substantially the instant when the current goes through zero or the polarity reverses, and the power curve reaches a maximum at substantially the instant when the current goes through the peak of any alternation.

ln one embodiment of our invention two are heaters, each connected by a rectifier to the same alternating current source, exhaust their gases into a large chamber where turbulent mixing occurs. The rectifier of one are heater is conductive only during a negative alternation of the alternating current, whereas the rectifier of the other are heater is conductive only during the positive alternation of the alternating current, so that each arc heater has a period where a relatively cold gas is exhausted therefrom followed by a period during which a relatively hot gas is exhausted therefrom. The hot gas volume from one are heater is mixed with the cold gas volume which emanates from the other are heater at the same time. Preferably the not and cold gases enter the mixing chamber from opposite sides, thus producing the best possible mixing.

Another embodiment of our invention employs a single are heater energized by alternating current and exhausting the gas into a bafiled expansion or mixing chamber, while still a third embodiment of our invention employs six are heaters exhausting into a single mixing chamber, the six are heaters being connected by rectifiers to the three phases of a three-phase alternating current source.

Accordingly, a primary object of our invention is to provide new and improved apparatus for the synthesis of a hydrocarbon by the pyrolysis of a process hydrocarbon.

Another object is to provide new and improved arc heater hydrocarbon pyrolysis and synthesis apparatus in which rapid heating and rapid cooling of gases occur periodically at a rapid rate.

Another object is to provide new and improved arc heater apparatus for use in synthesizing a hydrocarbon, in which dual arc heaters are employed to supply hot decomposed gas, and also cooling gas for cooling the decomposed hydrocarbon to some desired equilibrium temperature.

Still another object is to provide new and improved apparatus for use in hydrocarbon synthesis employing an arc heater system energized from a three phase alternating current source.

An additional object is to provide new and improved arc heater apparatus having regulation of the power cycle and especially suitable for use in carrying out a process for hydrocarbon synthesis.

A further object is to provide a new and improved method of hydrocarbon synthesis.

These and other objects will become more clearly apparent after a study of. the following specification, when read in connection with the accompanying drawings in which:

FIGURE 1a is an electrical schematic circuit diagram of arc heater apparatus according to a preferred embodiment of our invention;

FIG. 1b shows a modification of the circuit of FIG.

in which high frequency voltage generators are Provided for reigniting arcs which are extinguished during substantially a half-cycle of the alternating current;

FIG. 10 is a modification of the circuit diagram of FIG. la in which biased rectifiers are employed to modify the power cycle;

FlGS. 2, 3 and 4 are graphs illustrating the operation of the apparatus of FIGS. la, lb and 10;

FIG. 5 is a view in section of a suitable arc heater for practicing the present invention;

FIGS. 6a-6f contain time-spaced views of the exhaust from an arc heater in which the arc is produced by a single-phase alternating current;

FIG. 7 is a diagram of two arc heaters discharging into a single mixing chamber in accordance with the teachings of FIG. la;

FlG. 8a is a view of our invention according to an embodiment which uses a single arc heater energized from a single phase alternating current source;

FIG. 8b is a view of a modification of the are heater apparatus of FIG. 8a, in which a plurality of arc heaters discharge into a single mixing chamber;

FIG. 9a is a view of a modification of our invention in which six are heaters discharge into a single mixing chamber; and

FIG. 9!) is a schematic electrical circuit diagram of the apparatus of FIG. 9a.

Referring now to the drawings for a more detailed understanding of the invention, and in particular to FIG. la thereof, the reference numeral 210 generally designates a transformer having a core 211 and secondary 212, it being understood that the transformer has a primary, not shown for convenience of illustration, connected to an alternating current source, not shown for convenience of illustration. The electrodes of two are heaters generally designated 213 and 214 are shown, are heater 213 having electrodes 215 and 216, and are heater 214 having electrodes 217 and 218. Electrode 215 is connected by a lead 219 to one terminal of secondary 212, whereas electrode 216 is connected by way of rectifier 22}, lead 222, inductor 223 and lead 224 to the other terminal of secondary 212. Terminal 217 of arc heater 214 is connected to lead 219 whereas terminal 213 of arc heater 214 is connected by way of rectifier 226 to the aforementioned lead 222. It is noted that rectifiers 221 and 226 are of opposite polarity with respect to each other so that on one alternation of the current from secondary 212 and are takes place between electrodes 21.5 and 216 of arc heater 213, whereas on the next alternation of opposite polarity of the current from secondary 212, an arc takes place be tween electrodes 217 and 218 of arc heater 214. On the alternations during which the respective rectifiers 221 and 226 do not conduct, no arc takes place in the arc heaters 2.13 and 214. During these relatively idle periods, however, it will be understood that gas, under pressure, continues to be forced through the arc heaters 213 and 2E4. with the results that the exhaust from each of the arc heaters 213 and 214 consists of periodic masses of cold gas followed by periodic masses of hot gas.

Particular reference is made now to FIGS. 2, 3 and 4. In the operation of a single-phase alternating current are heater which does not use any rectifier, such as that shown in FIG. 8a hereinafter to be described, the arc current closely appoximates a sine wave, and the arc voltage roughly approximates a square wave in phase with the current. As a result the power is a somewhat distorted half-cycle sine wave. FIG. 2 schematically shows an idealized and somewhat simplified cycle alternating current power wave, wherein the wave repeats itself each half cycle; that is, times each second the power starts from zero, increases to some peak value, and decreases to zero again.

Since a hydrocarbon gas. for example methane, is continuously flowing through the heater, therewill be alternate hot and cold volumes of gas passing out of the heater if the gas residence time in the heater is comparable in duration to the time of one power cycle.

Particular reference is made now to FIGS. 6a-6f which show selected time-spaced views of the exhaust from a single-phase 60 cycle alternating current are heater, and represents the size of the exhaust which might be seen if views were taken at spaced time intervals of, for example, /4 of a second with an exposure time of 4 second. The exhaust of FIG. 6a may be thought of as occurring near the peak of the alternating current power cycle, whereas FIG. 6b shows a diminishing intensity as the power decreases, with FIG. 6c representing a view taken at approximately zero power. l iG. 6d represents a view taken at something less than a maximum, at a moment of time which does not correspond either to maximum or minimum power input; FIG. 6a represents a power input less than FIG. 6d, whereas in FlG. 6f, the power input has become maximum. 1t will be understood that the time interval between 6a and 6b may be considerably diflerent from the time interval between, for example, 6e and 6 in multiples of A second. The alternate hot and cold gas flow, as illustrated in FIGS. 6a6f, shows that which might be obtained with a 60 cycle alternating current are heater utilizing air as the working fluid. Since the air entering the heater is at approximately room temperature, it is possible, by thoroughly mixing the cold and the hotexit gas to rapidly quench the hot gas volume to a lower temperature.

Referring again to the curve of FIG. 2, which is a sinusoidal power vs. time wave, if his assumed that the gas has a roughly constant specific heat, and that how rate is constant, then the Zero power level in FIG. 2 can also represent the gas inlet temperature, T the peak of the power curve can also represent the top hot gas temperature, T,,, and the mean temperature after mixing will be about equal to T +(T --T) 2/1r.For this case, the temperature alter mixing is about 40% lower than the maximum temperature rise.

FIG. 2 may also approximate the total power curve for the rectifier arrangement of FIG. la, where alternate half cycles represent the power in two different are heaters. If more of a temperature reduction is required or desired, biased rectification can be employed such as that shown in FIG. lc hereinafter to be described in greater detail. The biased rectification can result in a power wave form as shown in FIG. 3 with a correspondingly greater rednction in top temperature after mixing.

Particular reference is made now to FIG. 1c which is similar to FIG. la, but in which biased rectifiers 236 and 238 are employed. As a result, the formation of an arc path through the electrodes 215 and 216 on one alternation, and the formation of an arc path through electrodes 217 and 218 on the next alternation is delayed by a small fraction of the alternation time, with the result that a no power gap exists between the alternations of the power curve of FIG. 3. The time duration of the intervals of substantially zero power can be controlled by controlling the value of the biases on the rectifiers 236 and 233. This also permits control of the temperature to which the mixed gases are cooled, and facilitates creating a temperature at which the desired gas is a stable recombination product.

' Particular reference is made now to FIG. 8a in which an additional embodiment of our invention is shown. An arc heater 242 with electrodes 240 and 241 connected to a single phase source of alternating current potential has an inlet 243 and a gas outlet or nozzle 244 emptying into a large mixing chamber 245. Mounted in the mixing chamber is a baflle 246 which is preferably wa ter-cooled, and for the purpose of cooling baffle 246, water inlet and outlet pipes 247 and 2.48 are shown passing through the wall 249 of the mixing chamber. The battle is disposed near and directly in front of the opening 250 through which exhausted gases from the arc heater 242 enter the mixing chamber 245. The mixing chamber 245 has an exhaust or 6 exit 251 in which is disposed an axially extending pipe 252 having a spray head 253 thereon, the pipe 252 bringmg a cooling fluid 254, such as cold water, which is sprayed mtogas passing through the exhaust vent 251, rapidly cooling the gases to, for example, a temperature of less that 1000 K. and preferably about 500 K. The final gas temperature can be controlled by selecting the water temperature and adjusting the rate of water flow, and these are contemplated as part of the invention. Also, preterably the pipe 252 may b moved so that the axial position of the spray head 253 along the longitudinal axis of the exhaust vent 251 may be adjusted for optimum cooling of the gases in a manner to provide the maximum amount of the desired gas product. Preferably, the spray head 253 directs the spray slightly toward the right, FiG. 811, so that no considerable portion of the fluid accumulates in the chamber 245. The chamber wall 249 may, if desired, have a very small drain opening or openings, not shown, in the bottom thereof or the exhaust tube 251 may be pitched Bil directed downward to prevent water entering chamber In the operation of the apparatus of FIG. 8a, methane may be supplied to inlet 243. Are heater 242 discharges alternate volumes of relatively hot and relatively cool gas as a result of the are therein being produced by an alternating current, as discussed in connection with FIG. 2 and FIGS. 6a6f inclusive. By providing suflicient are power, gas in heater 242. may be heated to over 3500 K. to dissociate the hydrocarbon into carbon and hydrogen atoms and molecules and free radicals such as CH, CH and CH The bafile 246 assists in turbulent mixing within the chamber 245 of the cold and hot and gases from the arc heater exhaust vent 244. In chamber 245, the hot and cold gases are rapidly mixed thus, in eflect, quenching the hot gas volume to a temperature between 2500 K. and 4200 K., and preferably close to 3600 K., at a pressure in the neighborhood of 1 atomsphere. Acetylene is a stable recombination species between 2500 K. and 4200 K., and may be in maximum concentration at about 3600" K. The quenched gas, that is, th product of the mixing in chamber 245, is then rapidly cooled to about 500 K. by the water spray 254. It is noted that the water spray is not directed into the very hot gas from the arc heater, that is, gas at a temperature greater than about 25-00 K., because if this were done, the water would dissociate into oxygen which would then react with the carbon to lower the yield of acetylene.

By providing an initial quenched temperature in chamher 245 of approximately 3600 K. which, corresponds to the temperature for equilibrium at maximum acetylene concentration, the methane entering inlet 243 is converted primarily to acetylene.

Certain considerations other than the temeprature at which the gas is dissociated may govern the choice of a temperature to which the gas is heated in the arc heater, so long as this chosen temperature is at least: as great as the dissociation temperature. In order that relatively discrete alternate volumes of cold and hot gas may comprise the are heater exhaust, the arc must be stable. To provide a stable arc, the gas in the vicinity of the electrodes and between electrodes must be ionized, and must remain ionized as the arc spots on the two electrodes travel from place to place as the arc moves. Where the electrodes are annular and the arc moves in an annular path around the electrodes, too low an initial gas temperature may result in so much of the hot ionized gas moving to the center of the electrode that it is diflicult to maintain the are as it rotates. A stable arc may be insured by heating the gas to an initial temperature of for example, 5000 K., although such a temperature is not required for dissociating the gas. It will be readily understood that the necessity for heating the gas to 5000 K. may req uired increased are power. For example, it has been found in practice with certain equipment that an input of one megawatt resulted in an unstable arc, whereas with the same equipment, an input of two megawatts gave a stable arc.

It will be apparent to those skilled in the art that the lower the mass flow through the arc heater, the greater will be the temperature to which the gas is heated. However, there is a certain minimum speed of gas flow through the arc heater set by the requirement that the quenched gas be cooled to below 1000 K. in less than one millisecond, in accordance with the dimensions of the mixing chamber and other considerations.

Generally speaking, it is desirable that the spray head 253 be as close to the entrance to the mixing chamber as possible to reduce the time required to cool the gas to prevent further chemical reactions.

Particular reference is made now to FIG. 8b. In FIG. 8b, in addition to are heater 242 having inlet 243 and outlet 244 communicating with chamber 245, it is understood that two other are heaters, not shown for convenience of illustration, operated in synchronism from the same alternating current source, supply inputs through conduits 257 and 258, the outputs of all three are heaters being combined in the turbulent mixing chamber 245. The wall of chamber 245' tape-rs to form an extended exit or exhaust portion 251 in which the pipe 252 is axially disposed and bears the spray head 253. The exhaust section 251 has a large conduit 261 connected thereto for removing the gas product of the process, and a small conduit 262 connected thereto for removing the water from spray 254.

Particular reference is made now to FIG. 7 wh1ch shows apparatus for practicing the invention as discussed in connection with FIG. 1a and FIG. 2. The are heater 213 having electrodes 215 and 216 is seen to have an inlet 264 for methane or other gas, and a gas outlet 265 exhausting into a mixing chamber 266. The aforementioned arc heater 214 having electrodes 217 and 218 is seen to have inlet 267 for methane or other gas and gas outlet 268 exhausting into the aforementioned mixing chamber 266. Chamber 266 has an exhaust nozzle portion 272 in which is disposed a spray head 271 connected to pipe 269 having valve 270 therein. Preferably the pipe 269 may undergo translator motion along its axis so that the position of the spray head 271 along the axis of vent or nozzle 272 may be adjusted. Arc heaters 213 and 214 are connected to the same alternating current source by way of oppositely poled rectifiers 221 and 226. At th same moment that are heater 213 is exhausting hot air into chamber 266, arc heater 214 is discharging relatively cold unheated air into the chamber 266 because at that instant, no arc is taking place between electrodes 217 and 218. Accordingly, there is a rapid cooling of gas in the chamber 266. By adjusting the speed of flow of gas through the two are heaters in accordance with the frequency of the alternating current applied between leads 219 and 222, and choosing the size of the mixing chamber 266, optimum operating conditions may be obtained. The hot portions of the gas streams through arc heaters 213 and 214 may reach temperatures in excess of 5000 K. and pyrolize the methane; in chamber 266, mixing may reduce the overall temperature to between 2500 K. and 4200 K., and preferably to about 3600 K. The spray head 271 supplies a spray which quickly cools the mixture to the desired temperature at which no further reaction occurs. It is desirable to cool the gas to below 1000 K. in less than 1 millisecond, and to cool it to 500 K. or below in 1 second.

The two inlets to chamber 266, that is inlet 265 and inlet 268, may be moved to any desired position around the periphery of the chamber 266 so that, if desired, the gas from the two arc heaters will come in from diametrically opposed positions.

Particular reference is made now to FIG. 5, which shows the interior of an arc heater suitable for use at 242 in FIGS. 8a and 8b, at 213 and 214 in FIG. 7; and at 301, 302, 303, 304, 305 and 306 in FIG. 9a. A most significant detail of the apparatus of FIG. is that the throat of the exhaust nozzle is relatively wide compared to the throat of the average gas are heater, so as not to restrict the flow of gas from the arc chamber 34 into the turbulent mixing chamber. Any suitable arc heater may be used at 242 in FIG. 8a, and the arc heater of FIG. 5 does not constitute part of the present invention, being described and claimed in the copending application of Charles B. Wolf and George A. Kemeny for Gas Arc Heater, Ser. No. 349,896, filed Mar. 6, 1964, and assigned to the assignee of the instant invention.

Referring now to the drawing of FIG. 5 for a more detailed understanding of the arc heater, there is shown generally designated 11 and 12 two cylindrical sections of arc heater chamber forming apparatus separated by a disc-like heat shield generally designated 13. The disclike heat shield may be composed, generally speaking, of two sections composed of different materials. The inner ring portion 14 may be composed of copper and have an annular passage 15 therearound for the passage of a cooling fluid, for example water, the passage 15 being connected with inlet and outlet means, one of these, for example inlet means 16, being shown. The outer portion of the heat shield 13 may be composed of other material which serves as a manifold and as one of the enclosing members of the arc heater cavity. The sides of the heat shield 13 are insulated from the adjacent cylindrical sections 11 and 12 by insulating discs 21 and 22 respectively.

The section through the lower portion of the ring 17 shows a radial inlet 24 for gas admission, the heat shield 13 having a transverse aperture or slot 25 therein making connection with the inlet 24 to provide two or more gas inlets for the heat shield. Aperture 25 forms a manifold with separate small holes 29 and 30 so as to effect near uniform air admission into the arc heater cavity. Holes 29 and 30 are positioned at spaced intervals along the air header 25 so that gas to be heated is uniformly admitted at a plurality of points around the peripheries of annular ridges 48 and 68. It will be understood that since lnlet and outlet radial conduits are provided for water passage 15, that two air headers, each substantially semicircular, are provided.

It will be understood that whereas a minimum of two radially extending conduits 16 are needed for cooling passage 15, and a minimum of two air headers are thus necessitated, a number of gas inlets may be provided at spaced peripheral intervals around the heat shield, and likewise more than one water inlet and more than one water outlet may be provided for the coolant flow passage 15.

Theinsulating discs 21 and 22 terminate at their inner edges in a pair of O-ring seals 27 and 28 respectively. These O-rings may be further protected from radiation by insulating rings 113 and 114 which may be of ceramic material or other insulation.

The section of the chamber wall generally designated 11 is seen to comprise, generally speaking, two portions, an outer portion 31 which may be of, for example, steel and may be ferromagnetic material, and an inner portion 32 of, for example, copper. The copper portion 32 is seen to have a thin wall portion 33 adjacent the arc chamber 34, and it is seen that directly behind the thin wall portion 33 is a cylindrical passage 35 shaped generally to the countour of the wall of portion 32. The passage 35 which as before mentioned may be cylindrical in shape and extend around the entire circumference f the wall portion, is provided for the flow of cooling Water which may enter the annular or ring shaped water passage 37 by way of inlet conduit 38 and exit from the annular or ring shaped water passage 36 by Way of exit conduit 39. The outer chamber wall portion 31 is shown to have sealing means such as O-rings at 41, 42, 43, and 44 for providing seals between the outer section 31 and the inner section 32. Disposed in an annular recess 45 in portion 32 is a field coil 46 provided for purposes to be made hereinafter more clearly apparent. It is seen that the outer wall contour of wall portion 33 comes to a peak 48 overhanging the air space which separates the heat shield 13 from the cylindrical portion 11 on that side thereof. This peak 48 is provided to insure optical baffing for the insulating member 113, and O-ring 27 so that direct radiation from the are 49 in the are chamber 3 1 and direct radiation from heated gas in the vicinity of the are 49, does not fall upon the insulating member 113 1 O-ring 27. Wall surface 50 is rounded and conforms very closely to the path of the magnetic flux in this area.

Oppositely disposed with respect to the cylindrical wall section 11 is the aforementioned cylindrical Wall section 12, which may be substantially identical with the section 11 but with ends reversed to provide the symmetrical arrangement shown. Section 12 has an outer portion 51 and an inner portion 52 with a thin wall portion 53. Adjacent the wall portion 53 is a cylindrical cooling passage 55, having an inlet 56 connected to inlet conduit 58. Sealing O-rings 61, 62, 63, and 64 are provided, and a field coil as is provided as shown in recess 65. The wall portion '53 also has a peak portion 68 for providing optical battling for the insulating member 114 or O-ring 28. Wall surface so is curved to the curvature of the magnetic field from coil as.

The field coils 4'6 and 66 may be so excited that their fields oppose each other, with the result that the magnetic lines of force are substantially perpendicular to the arc direction of the are shown at 43.

Coils 4s and 66 are energized by direct current, and produce a magnetic field which causes the arc to move continuously around the chamber walls.

As previously stated, the cylindrical wall sections generally designated 11 and 12 constitute parts of an electrical circuit, and the thin wall portions 33 and 53 of these sections constitute the electrodes between which the are 19 occurs. Accordingly, sections 11 and 12 are insulated from each other by the aforementioned insulating discs 21 and 22. Likewise, section 11 is insulated by insulating gasket 72 from a chamber plug generally designated 70 which is utilized to enclose one end of the arc chamber 34, and section 12 is also insulated from a nozzle generally designated 71 at the other end of the are chamber by insulating gasket 73.

The plug 70 is seen to consist of a heat transferring cylindrical portion 75 with a flange 76, this portion 75 being composed of, for example, copper. The inside end of the portion 75 is seen to be relatively thin but yet thick enough to withstand the pressure generated in the arc chamber without being bent towards the left against the remainder of the plug. The outer portion of the plug is generally designated 77, and is cylindrical in shape, with a central bore 78. Water or other cooling fluid may be admitted through the bore 78, flowing around the annular or cylindrical passage 75? and out of the water header 80 and outlet passage 81. A sealing ring 82 is provided as shown, as is the sealing ring 83, both in annular grooves. It is seen that the sealing ring 32 is optically baflled so that it receives no direct radiation from the are 49 in the chamber 34. If desired, cold gas may be admitted in the annular gap between members 75 and 33 to further provide electrical insulation between members 11 and 7 and to prevent deposition of contaminants in the annular gap and on O'ring 112, any suitable means, not shown for convenience of illustration being provided for this purpose.

The nozzle generally designated 71 is insulated as aforementioned from the adjacent chamber wall section 12 by the insulating disc 73 having the O-ring seal 35. The O-ring 85 is optically baffled so that it does not receive direct radiation from the are 4'? in the chamber 34. It is seen that a small space 86 exists between the adjacent wall of the nozzle 71 and the inner wall portion 53 of the cylindrical section 12 to provide the aforementioned necessary electrical insulation. If desired, cold gas may be admitted into annular gap 86 to further provide electrical insulation and prevent deposition of contaminants in gap .36 and on O-ring 85, any suitable means, not shown for convenience of illustration, being provided for this purpose. Nozzle '71 has a vent or exhaust passage 88 and has thin wall portion 89 adjacent the exhaust or vent 88 to provide for maximum cooling. Behind the wall portion 39, which is substantially conical in shape, is a passage 91) for the flow of cooling fluid such as water, water being admitted to header 91 by inlet conduit 93 and exhausted from outlet conduit 94 by way of water header 92.

It is seen that the chamber section 12 has at any suitable point therein a channel or passageway 96 through which electrical connections 97 are made to the field coil 66. An additional passageway, not shown, similar to the passageway 96 is provided in chamber section 11 for bringing leads separately to the field coil 46.

Clamping means, not shown for simplicity of illustratration, is provided for applying clamping forces which will tightly hold the sections 11 and 12 against the insulating discs 21 and 22 and firmly hold the heat shield 13 in place against the large pressures created in the arc chamber, while maintaining electrical insulation between sections 11 and 12. In addition, means, not shown for convenience of illustration, is provided for clamping the chamber plug generally designated and the nozzle generally designated 71 to the assembly, while maintaining plug 77 electrically insulated from section 11, and maintaining nozzle 71 electrically insulated from wall section 12. Both of the aforementioned clamping means may consist of a pair of ring members or ring means, insulated if desired, disposed at each end of the arc chamber apparatus, having a plurality of peripherally spaced holes through which bolts, insulated if desired, pass, which extend the length of the arc chamber and are firmly secured by nuts at the opposite ends, the rings firmly pressing against surfaces 101 and 1112, and against the outer surface 163 of plug 70 and the end surface 104 of nozzle 71. Plug 7E may also be secured to wall portion 11 by suitable insulated bolts and nozzle 71 may be similarly attached to chamber section 12 through a separate set of bolts.

In the operation of the apparatus, prior to the admission of gas, the plug generally designated 70 may be removed after the clamping pressures thereon are released, and the arc chamber inspected and a shooting wire introduced between the wall portions 33 and 53 for starting the are when a potential is applied to the electrodes. The plug is thereafter secured in place. Electrical connections to sections 11 and 12 are provided at 111 and 112, but other suitable electrical connections could be provided if desired. Thereafter, gas is admitted through the inlets 24 and a potential applied to input leads 111 and 112 to generate a potential across electrode surfaces 33 and 53. The are is started simultaneously therewith or shortly after the magnetic field is set up by energizing coils 46 and 66. The gas admitted at 24 moves the arc toward the center of the arc chamber. As previously stated, gas admission may be tangential to enhance mixing and are movement.

The plug and the nozzle both have what in effect are coolant manifolds.

As previously stated, it will be understood that the bolts and clamps utilized to clamp the assembly together may be themselves insulated to provide the necessary insulation between portions of the arc chamber structure.

The apparatus is readily suitable to single-phase alternating current, or to any selected phase of a three phase source. The arc length may be varied within limits by making the ring member 13 thicker or thinner as desired or by adding additional rings similar to 13 between members 11 and 12.

Particular reference is made now to FIG. 9a. Six similar arc heaters 301, 302, 3G3, 394, 305 and 306, having inlets for methane or other gas 311, 312, 313, 314, 315 and 316 respectively deliver their gas outputs through outlets 321, 322, 323, 32 i, 325 and 326 respectively to a single turbulent mixing chamber 328. The turbulent mixassures iii ing chamber 328 has an exhaust vent 336 with fluid conduit 331 axially disposed therein, having spray head 332.

In actual practice, the turbulent mixing chamber 323, which is shown as spherical in FIG. 90, might be cylindrical with three of the are heaters coming in at circumferentially spaced positions 120 apart in one plane normal to the longitudinal axis of the mixing chamber, whereas three other are heaters are circumferentially spaced 120 apart in another parallel plane passing through the axis of the cylindrical mixing chamber and substantially perpendicular thereto.

Particular reference is made to FIG. 9b, which shows a three-phase alternating current circuit for energizing the arc heaters of FIG. 9a. In FIG. 91), three Y-connected primary windings 341, 342, and 343 are connected by leads 344, 345 and 346 respectively to a source of threephase alternating current. Secondaries 347, 348 and 349 are delta connected, and across secondary 347 are connected the electrodes of are heaters 302 and 355 having rectifiers 352 and 355 in series therewith. Across the secondary 348 there are connected arc heaters 303 and 306 having in series therewith respectively rectifiers 353 and 356. Across the secondary 349 there are connected arc heaters 301 and 304 having in series therewith respectively rectifiers 351 and 354. As previously stated, because of the polarities of the rectifiers any pair of arc heaters con nected across a secondary alternately supply hot blasts of air as their outputs, and any pair alternately supply relatively cold blasts as their outputs. Accordingly the exhausts of arc heaters 304 and 361 are preferably diametrically disposed, so that at the moment that are heat er 304 is discharging hot gas into the turbulent mixing chamber 328, the arc heater 301 is discharging relatively cold air into the mixing chamber 328. The gas mixture is quenched or cooled in the mixing chamber, and further cooled by the water spray. The desired product output, acetylene, is obtained from the vent 330. For stable arc operation, inductors are required in series with the are. In FIG. 9b, the transformer can be wound with a high inductance winding thus eliminating the need for additional series inductance.

As previously stated, for large blocks of power the single-phase voltage and current wave forms required to produce the power wave form shown in FIG. 2 introduce an undesirable system load, when apparatus according to FIG. 8a is employed. A similar single-phase load is obtained by use of the apparatus of FIGS. 7 and 1c, in which a power wave form corresponding to that shown in FIG. 3 is obtained. When a hookup is made in accordance with the showing of FIG. 7, each arc heater has a power wave as shown in FIG. 4. The mean temperature of the efiiuent gas is now only about T +(T -T 1/12 As previously stated, for very large blocks of power, six are heaters may be used in accordance with the showing in FIG. 9a. By discharging the separate heaters into a single mixing chamber, rapid mixing and quenching of the slugs of hot gas are assured. By using six heaters, the desired three phase balanced load can be obtained.

For further example, with two are heaters, the heater exits can be made to oppose in the mixing chamber which will, automatically for the FIG. 7 configuration, shoot the hot gas volume of one heater against the cold gas volume which emanates from the other heater at the same time thus producing the best possible mixing.

As will be readily understood by those skilled in the art, the longer the time interval during which no current flows in an arc heater, the more ditiicult it becomes to reignite the are for the next cycle. Particular reference is made now to FIG. 1b, which shows an electrical circuit diagram for utilizing a superimposed very high frequency low current source of power. In FIG. 11), there is seen to be a high frequency choke capable of carrying a very large direct current and having substantially no reactance at the alternating current power frequency interposed between rectifier 221 and electrode 216, and

there is a similar high frequency choke 232 interposed between rectifier 226 and electrode 218 of arc heater 214. The use of these chokes is actually desired for stable arc operation. Separate high frequency generators 229 and 230 are provided for the two are heaters, their outputs being coupled by capacitors 233 and 234 respectively, to the electrodes 216 and 213, respectively. Capacitors 233 and 234 have very high reactance values at the alternating current power frequency, so that substantially no component of power frequency flows through the high frequency generators. On the other hand, capacitors 233 and 234 have capacitance values sufiiciently large to offer a very small. impedance to the flow of the high frequency signals generated at 229 and 239. These are of sufiicient voltage to maintain an arc across the electrodes of the respective are heaters during those portions of the alternating current power frequency cycle, when the respec tive rectifiers 221 and 226 prevent the flow of alternating current of power frequency through the electrodes, and the high current and high power arcs resulting from the power frequency are extinguished. It will be understood that the high frequency low power arcs are maintained at substantially all times so that immediate reignition occurs when the alternation of the power frequency is or" the correct polarity to pass through the respective rectifiers. It will be further understood that the high frequency arcs themselves have no substantial current and produce no substantial heating of the gas passing through the arc heater.

As previously stated, in converting methane to acetylene, equilbirum for maximum concentration of acetylene as a recombination product occurs at about 3600 K. at one atmosphere of pressure. The time of passage of gas through the arc heaters may be varied, as by selecting the inner diameters of the inlets and outlets, the inlet gas pressure, and the power of the are, to pyrolize the methane and quench it to a suitable temperature, depending on the embodiment used. When biasing is used, the time intervals of the power cycle may be adjusted to give the desired quench temperature in the mixing chambers.

In FIG. 8b, battle 246 may be dispensed with if not needed.

Whereas the invention has been described with reference to pyrolizing methane to obtain acetylene as a recombination product, other hydrocarbons and gases may also be utilized to produce acetylene, suitable temperatures being provided. At suitable temperatures, usually lower, other hydrocarbon products, for example, ethylene, may also be produced by the pyrolysis.

Whereas we have shown and described our invention with respect to some embodiments thereof which give satisfactory results in the practice of the method of the invention, it should be understood that changes may be made and the equivalents substituted without departing from the spirit and scope of the invention.

We claim as our invention:

ll. In apparatus for synthesis of a gas, in combination, a first arc heater having a pair of electrodes, a gas inlet and a gas outlet, 21 second arc heater having a pair of electrodes, at gas inlet and a gas outlet, a turbulent mixing chamber, the gas outlets of the first and second arc heaters being operatively connected to the turbulent mixing chamber whereby the exhaust of the first arc heater and the exhaust of the second are heater both enter the turbulent mixing chamber, first rectifier means operatively connecting the electrodes of the first arc heater to a source of single-phase alternating current potential, second rectifier means operatively connecting the electrodes of the second arc heater to the sam source of single-phase alternating current potential, the first rectifier means and the second rectifier means being oppositely poled with respect to each other whereby an arc occurs across the electrodes of the first arc heater only during an alternation of one polarity of the alternating current and an arc occurs across the electrodes of the second arc heater only 13 during an alternation of opposite polarity of the alternating current, exhaust means for the turbulent mixing chamber, and means for spraying a cooling fluid into the gases being exhausted from the exhaust means of the turbulent mixing chamber.

2. Gas synthesis apparatus comprising in combination, a turbulent mixing chamber, a first arc heater having a pair of electrodes, a gas inlet and a gas outlet connected to the mixing chamber, a second arc heater having a pair of electrodes, a gas inlet and a gas outlet connected to the mixing chamber, the outlet of the first arc heater and the outlet of the sec-ond arc heater entering the turbulent mixing chamber at substantially diametrically opposed positions with respect to each other, first biased rectifier means operatively connecting the electrodes of the first arc heater to a source of single-phase alternating current potential, second biased rectifier means operatively connecting the electrodes of the second arc heater to the same source of single phase alternating current potential, the first biased rectifier means and the second biased rectifier means being oppositely poled with respect to each other whereby an arc occurs across the electrodes of the first arc heater only during an alternation of one polarity of the alternating current and an arc occurs across the electrodes of the second arc heater only during a alternation of opposite polarity of the alternating current, the first and second biased rectifier means providing that a time interval elapses between the end of an arc resulting from the alternation of one polarity of the alternating current and the beginning of an are resulting from an alternation of opposite polarity of the alternating current, exhaust means for the turbulent mixing chamber, and means for spray-ing a cooling fluid into the gases being exhausted through the exhaust means from the turbulent mixing chamber.

3. Gas synthesis apparatus comprising, in combination, a first arc heater having a pair of electrodes, a gas inlet and a gas outlet, a second arc heater having a pair of electrodes, a gas inlet and a gas outlet, a turbulent mixing chamber, the outlet of the first arc heater and the outlet of the second arc heater both opening onto the turbulent mixing chamber at substantially diametrically opposed positions, first biased rectifier means connecting the electrodes of the first arc heater to a source of single phase alternating current potential, second biased rectifier means connecting the electrodes of the second arc heater to the same source of single phase alternating current potential, the first biased rectifier means and the second biased rectifier means being oppositely poled with respect to each other whereby an arc occurs across the electrodes of the first arc heater only during an alternation of one polarity of the alternating current and an arc occurs across the electrodes of the second arc heater only during an alternation of opposite polarity of the alternating current, the first and second biased rectifier means insuring that a time interval elapses between the end of an arc in the first arc heater and the beginning of an arc in the second are heater, exhaust means for the turbulent mixing chamber, and means for spraying a cooling fluid into the gases being exhausted from the exhaust means of the turbulent mixing chamber.

4. Gas synthesis apparatus comprising, in combination, a first arc heater having a pair of electrodes, a gas inlet and a gas outlet, a second arc heater having a pair of electrodes, a gas inlet and a gas outlet, turbulent mixing chamber, the outlet of the first arc heater and the outlet of the second arc heater both opening into the turbulent mixing chamber at substantially diametrically opposed positions, first rectifier means connecting the electrodes of the first arc heater to a source of alternating current potential of power frequency, second rectifier means connecting the electrodes of the second are heater to the same source of alternating current potential of power frequency, the first rectifier means and. the second rectifier means being oppositely poled with respect to each other whereby an arc occurs across the electrodes of the first arc heater only during an alternation of one polarity of the alternating current and an arc occurs across the electrodes of the second arc heater only during an alternation of opposite polarity of the alternating current, first high frequency generator means operatively connected across the electrodes of the first arc heater, second high frequency generator means operatively connected across the electrodes of the second arc heater to provide first and second high frequency voltages for substantially instantaneously starting the arcs across the electrodes of the first and second arc heaters at the beginning of alternations of both polarity of the power frequency without waiting for the voltage across the electrodes to attain a substantial value, exhaust means for the turbulent mixing chamber, and means for spraying a cooling fluid into the gases being exhausted from the exhaust means of the turbulent mixing chamber.

5. Gas synthesis apparatus according to claim 4 including in addition first and second inductor means connected in series with the first and second rectifier means respectively for preventing the high frequency voltages of the first and second high frequency generators from entering the alternating current source.

6. Gas synthesis apparatus comprising, in combination, a first arc heater having a pair of electrodes, a gas inlet and a gas outlet, a second arc heater having a pair of electrodes, a gas inlet and a gas outlet, a third are heater having a pair of electrodes, a gas inlet and a gas outlet, a three phase source of alternating current potential, circuit means connecting the first, second and third are heaters to the three phase source of alternating current potential, a turbulent mixing chamber, the gas outlets of the first, second and third are heaters being operatively connected to the mixing chamber, means forming a tubular exhaust passageway connected to the mixing chamber, and means for spraying gas passing through the tubular exhaust passageway with a cooling fluid.

'7. Gas synthesis apparatus comprising, in combination, a first arc heater having a pair of electrodes, at gas inlet and a gas out-let, a second arc heater having a pair of electrodes, a gas inlet and a gas outlet, a third arc heater having a pair of electrodes, a gas inlet and a gas outlet, a fourth :arc heater having a pair of electrodes, a gas inlet and a gas outlet, a fifth arc heater having a pair of electrodes, a gas inlet and a gas outlet, a sixth arc heater having a pair of electrodes, 21 gas inlet and a gas outlet, means connected to each of the arc heaters for producing an arc therein intermittently varying in power whereby gas from the outlet of the are heater consists of alternate relatively cold portions and relatively hot portions, a turbulent mixing chamber, all of the gas outlets of the first, second, third, fourth, fifth and sixth arc heaters opening into the turbulent mixing chamber, passage forming means operatively connected to the turbulent mixing chamber for exhausting gases therefrom, and means extending into the passage for spraying a cooling liuid into the gases as they move through the passage.

8. Gas synthesis apparatus comprising, in combination, a first arc heater having a pair of electrodes, a gas inlet and a gas outlet, a second arc heater having a pair of electrodes, at gas inlet and a gas outlet, at third are heater having a pair of electrodes, a gas inlet and a gas outlet, a fourth arc heater having a pair of electrodes, a gas inlet and a gas outlet, :a fifth arc heater having a pair of electrodes, a gas inlet and a gas outlet, a sixth arc heater having a pair of electrodes, a gas inlet and a gas outlet, a three phase source of alternating current potential, a first and second rectifier means connecting the electrodes of the first and second arc heaters in parallel across one phase of the three phase source, the first and second rectifier means being oppositely poled with respect to each other, third and fourth rectifier means connecting the electrodes of the third and fourth arc heaters in parallel across a second phase of the three phase source,

the third and fourth rectifier means being oppositely poled with respect to each other, fifth and sixth rectifier means operatively connecting the electrodes of the fifth and sixth arc heaters respectively in parallel across the third phase of the three phase source, the fifth and sixth rectifier means being oppositely poled with respect to each other, a turbulent mixing chamber having the gas outlets of all of the first, second, third, fourth, fifth and sixth arc heaters opening thereinto, means for removing gas from the turbulent mixing chamber, and means for spraying a cooling fluid into the gas as it is removed from the turbulent mixing chamber.

9. Apparatus according to claim 8 additionally characterized as having the outlets of the first and second arc heaters entering the turbulent mixing chamber at substantially diametrically opposed positions with respect to each other, the gas outlets of the third and fourth arc heaters entering the turbulent mixing chamber at substan tially diametrically opposed positions with respect to each other, and the gas outlets of the fifth and sixth arc heaters entering the turbulent mixing chamber at substantially diametrically opposed positions with respect to each other.

it Apparatus according to claim 8 in which the first, second, third, fourth, fifth and sixth rectifier means are additionally characterized as being biased whereby time intervals are made to exist between arcs resulting from alternations of opposite polarity of the first phase of the three phase source, between alternations opposite polarity of the second phase of the three phase source, and between alternations of opposite polarity of the third phase of the three phase source.

11. Apparatus according to claim 3 including in addition high frequency generator means operatively connected to the electrodes of the first, second, third, fourth, fifth and sixth arc heaters for applying high frequency voltages of very low current thereaoross respectively, the high frequency Voltages insuring that the arcs between electrodes start without waiting for the alternating current voltage of power frequency to attain a substantial value at the beginning of each alternation.

12. Gas synthesis apparatus comprising in combination, are heater apparatus, means for passing a stream of gas through the arc heater apparatus, the arc heater apparatus being constructed and arranged to heat alternate portions of the gas stream to relatively cold and relatively hot temperatures, the relatively hot temperatures being sufiicient to produce pyrolysis, and a mixing chamber operatively connected to the arc heater to receive the output thereof, the relatively cold portions mixing with the relatively hot portions in the mixing chamber and quenching the same to a predetermined lower temperature.

13. "Hychocarbon conversion apparatus comprising, in combination, a first arc heater having a hydrocarbon gas admitted thereto, a second arc heater having the same kind of hydrocarbon gas admitted thereto, turbulent mixing chamber means operatively connected to the first and second arc heaters, the first and second arc heaters including electrical power means and being constructed and arranged to alternately provide periodic volumes of heated gas into the turbulent mixing chamber, one are heater supplying relatively hot gas at the same instant that the other are heater supplies relatively cold gas to the turbulent mixing chamber, the gases of both the first and second arc heaters rapidly mixing in the turbulent mixing chamber with an overall cooling thereof, exhaust means for the turbulent mixing chamber, and fluid spray means in the exhaust means for spraying a cooling fiuid into the gas mixture passing therefrom, said gas mixture containing a large proportion of the desired conversion product, the fluid rapidly cooling the mixture and resulting in stabilization of a large portion of the conversion product.

14. Gas synthesis apparatus comprising, in combination, are heater means including first and second electrodes and a source of potential for producing an arc between the electrodes, the arc heater means including gas inlet means and gas outlet means, mixing chamber means connected to the gas outlet means, the arc heater means being constructed and arranged whereby gas entering the gas inlet means is discharged through the gas outlet means as a gas stream having some periodic portions at a relatively high temperature andother periodic portions at a relatively low temperature, the periodic portions and other periodic portions mixing in the mixing chamber to provide gas at a temperature intermediate said high and said low temperatures, and means for further cooling the last named gas as it leaves the mixing chamber.

15. Gas synthesis apparatus comprising, in combination, a first are heater having a pair of electrodes, 21 gas inlet and a gas out-let, a second arc heater having a pair of electrodes, at gas inlet and a gas outlet, a turbulent mixing chamber, the outlet of the first are heater and the outlet of the second arc heater entering the turbulent mixing chamber at substantially diametrically opposed positions, first rectifier means connecting the electrodes of the first arc heater to a source of single phase alternating current potential, second rectifier means connecting the electrodes of the second arc heater to the same single phase source of alternating current potential, an inductor interposed between both the first rectifier means and the second rectifier means and the single phase source, the first rectifier means and the second rectifier means being oppositely poled with respect to each other whereby an arc occurs across the electrodes of the first are heater only during an alternation of one polarity of the alternating current and an arc occurs across the electrodes of the second arc heater only during an alternation of opposite polarity of the alternating current, said inductor modifying the normal power cycle of both the first and second arc heaters, exhaust means for the turbulent mixing chamber, and means for spraying a cooling fluid into gases passing through the exhaust means.

16. The method of pyrolizinga hydrocarbon gas to form acetylene which comprises the steps of obtaining as a first part of the gas to be pyrolized a stream of alternate hot and cold portions, obtaining as a second part of the gas to be pyrolized another stream containing alternate hot and cold portions, the hot portions of both streams being raised to a temperature sufficient to pyrolize the gas, the hot portions of one stream occurring substantially simultaneously with the cold portions of the other stream, mixing the portions of one stream with the portions of the other stream to form a volume of gas cooled to a temperature within the range of temperatures at which acetylene is a stable recombination product, and thereafter spraying a cooling fluid into the cooled volume of gas to further cool the gas and prevent substantial further chemical reaction of the acetylene.

17. The method of pyrolizing a process hydrocarbon gas to form another desired gas which comprises the steps of passing one portion of the process hydrocarbon gas through an electric arc which is periodically varying in intensity to form alternate relatively hot and relatively cold volumes of gas, passing another substantially equal portion of the process hydrocarbon gas through an additional electric are which is periodically varying in intensity to form alternate relatively hot and relatively cold volumes of gas, the relatively hot volumes passed through one are occurring substantially simultaneously with the relatively cold volumes passed through the other are, mixing the hot and cold volumes to produce a gas temperature within the range of temperatures at which the desired gas is a stable recombination product, and thereafter quickly cooling the mixture to stabilize a substantial portion of the desired gas and prevent substantial further chemical reaction of the desired gas.

18. The method of synthesizing a desired gas from a process gas containing all the elements of the desired gas,

comprising passing the process gas through :an electric are which periodically varies in power to form a stream of the process gas having alternate relatively cold portions and relatively hot portions heated to a temperature at which pyrolysis occurs, and mixing the relatively cold portions with the relatively hot portions to quench the hot portions and form a mixture .at a temperature at which the desired gas is a stable recombination product.

19. The method of synthesizing a desired gas from a process hydrocarbon gas containing all the elements of the desired gas, which includes the steps of passing two streams of the process gas separately through two electric arcs each of which periodically varies in power, an increase in power in one are occurring substantially simultaneously with a decrease in power of the other arc, to form first and second streams of the process gas each having alternate relatively cold portions and relatively hot portions heated to a temperature at which dissociation of the molecules to carbon and hydrogen atoms and free radicals occurs, the cold portions of the first stream occurring substantially simultaneously with the hot portions of the second stream, and thereafter substantially continuously mixing gas from the first and second streams whereby the cold gas of one stream quenches the hot gas of the other stream to form a mixture at a temperature within the range of temperatures at which the desired gas is a stable recombination product.

20. The method of synthesizing acetylene from methane which includes the steps of passing methane gas through an electric are which periodically varies in power to form a gas stream having alternate relatively cold portions and relatively hot portions heated to a temperature at which dissociation of the molecules to carbon and hydrogen atoms and free radicals occurs, and mixing the relatively cold portions with the relatively hot portions to quench the hot portions and form a mixture at :a temperature within the range of temperatures at which acetylene is a stable recombination product.

21. Gas synthesis apparatus comprising, in combination, an arc heater having gas inlet means and gas outlet means, means connected to the arc heater for producing an arc therein periodically varying in power whereby gas from the outlet means consists of alternate relatively cold portions and relatively hot portions, a turbulent mixing chamber having the gas outlet means connected thereto, a fluid cooled battle disposed in the turbulent mixing chamber in a position whereat substantially all of the heated gas from the arc heater entering by way of the outlet means impinges against the bafiie, the turbulent mixing chamber having an opening therein for the escape of gas therefrom, exhaust passageway forming means connected :to said opening, and fluid spray means disposed within the exhaust passageway forming means for bring- 18 ing a cooling fluid and spraying the fluid into gas moving through said passageway.

22. Gas synthesis apparatus comprising, in combination, a first arc heater having a pair of electrodes, a gas inlet and a gas outlet, a second arc heater having a pair of electrodes, a gas inlet and a gas outlet, a third arc heater having a pair of electrodes, a gas inlet and a gas outlet, a fourth arc heater having a pair of electrodes, a gas inlet and a gas outlet, a fifth arc heater having a pair of electrodes, at gas inlet and a gas outlet, a sixth arc heater having a pair of electrodes, a gas inlet and a gas outlet, a three phase source of alternating current potential, first and second rectifier means connecting the electrodes of the first and second arc heaters respectively in parallel across one phase of the three phase source, the first and second rectifier means being oppositely poled with respect to each other, third and fourth rectifier means connecting the electrodes of the third and fourth arc heaters respectively in parallel across another phase of the three phase source, the third and fourth rectifier means being oppositely poled with respect to each other, fifth and sixth rectifier means connecting the electrodes of the fifth and sixth arc heaters respectively in parallel across the third phase of the three phase source, the fifth and sixth rectifier means being oppositely poled with respect to each other, a turbulent mixing chamber, all of the gas outlets of the first, second, third, fourth, fifth :and sixth arc heaters opening into the turbulent mixing chamber, the gas exhausts of the first and sec-0nd arc heaters entering the turbulent mixing chamber at substantially diametrically opposed positions, the gas exhausts of the third and fourth :arc heaters entering the turbulent mixing chamber at substantially diametrically opposed positions, the gas exhausts of the fifth and sixth arc heaters entering the turbulent mixing chamber at substantially diametrically opposed positions, passage forming means operatively connected to the turbulent mixing chamber for exhausting gases therefrom, and means extending into the passage for spraying a cooling fluid into the gases as they move through the passage.

References Cited UNITED STATES PATENTS Re. 25,218 8/1962 Schallus et a1. 260-679 2,884,472 4/ 1959 B-ludworth 260--679 3,168,592 '3/1965 Cichelli et a1. 260-679 FOREIGN PATENTS 938,823 10/1963 England.

DELBERT E. GANTZ, Primary Examiner.

J. D. MYERS, A ssistmzl Examiner. 

